Exemplary embodiments herein generally relate to a side curtain airbag, and more particularly, to an automated vision inspection of a side curtain airbag assembly for detecting whether a cushion of the side curtain airbag assembly is in a twisted state at the time of installation.
The side curtain airbag assembly is a common safety device applied to passenger vehicles and is deployed to protect the occupants of the vehicle from a side impact head injury and to resist ejection from the vehicle in the case of a rollover. Generally, the side curtain airbag assembly includes a cushion, an inflator, mounting hardware and a variety of other hardware based on the requirements of the application. When the side curtain airbag assembly is manufactured, the cushion is rolled or folded to minimize the space occupied by the device in the vehicle. In some designs, the rolled or folded cushion is covered by a sock. The sock is a sleeve of material which has a sewn seam or perforated line which ruptures when the inflation of the cushion begins. The side curtain airbag assembly is installed in a manner that the device begins generally at the base of the A-pillar (front), up the A-pillar, along the length of the roof, down the rear pillar (B, C or D) and ends at the rear of the passenger compartment. In the simplest arrangement, the side curtain airbag assembly is long (two to four meters), slender (30 to 120 millimeters in circumference), and quite flexible (bend and twist). Due to its flexibility, installation must be done carefully to ensure the side curtain airbag assembly is not mounted to the vehicle with a longitudinal 360 degree twist imparted to the cushion. A twisted cushion may not deploy properly and thus may not provide the desired passenger safety protection.
To ensure proper installation, various vehicle manufactures have applied markings to the cushion and/or cover to make recognizing a twist with the human eye easier. Other manufacturers have employed hardware added to the side curtain airbag assembly to make imparting a 360 degree twist difficult. In some cases, the additional hardware is quite extensive and thus adds weight and cost to the side curtain airbag. Therefore, it is desirable to eliminate such weight and cost as long as other measures are taken to ensure a proper installation of the side curtain airbag. Automated vision inspection offers such protection, but while the technology is robust enough to detect a twisted installation, the technology is prone to false detections. False detections are disruptive to manufacturing operations and thus resistance to application of vision inspection technology exists.
Automated vision inspection involves the capture of digital images of the installed side curtain airbag assembly and processing those images through imaging processing software that has been programmed to look for key features previously defined and to assess the installed condition by comparison of the current image to a master image. Due to the flexible nature of the side curtain airbag assembly, each installation is unique and thus, the master image would only give a satisfactory judgment when compared to itself. Therefore, for automated inspection, it is important to provide the image processing software with markings on the device that do not appear elsewhere in the image and that can be found by the vision inspection software and evaluated for presence and position.
Traditional markings on the side curtain airbag assembly such as barcodes, writing (in any language) or stripes can be used to assist the human eye in detecting twists, but fail to reliably prevent misinterpretation of features in the image when utilizing an automated vision inspection system. For example, in the case of a longitudinal stripe, the two dimensional appearance of the edge of the stripe can appear similar to the edge of the side curtain airbag against the vehicle body. Likewise, the shadow cast by the side curtain airbag can appear as a stripe. Also, the edge features of the vehicle, such as a door opening, can create a line that can be misinterpreted as a cushion stripe. Further, writing on the cushion of the side curtain airbag can create different possibilities of misinterpretation. For example, and as depicted in FIG. 14, consider a cushion with a series of letters or words printed on its entire length. A twisted installation of the cushion would create a gap in the words or letter string. However, if the words are arranged into a phrase, the natural gap between words can be misinterpreted as gaps created by a twisted installation. And, many Roman letters, such as the letter “S”, have rounded sides. These rounded sides can make determining the bottom and side of the mark difficult, and therefore determining orientation can be difficult. In addition, geometric shapes provided on a length of the side airbag cushion can have issues in interpretation. First, many of these geometric shapes appear in the vehicle in other locations. For example, round, triangular, rectangular and square holes are generally stamped into the vehicle body. Bolts with hexagonal heads, hexagonal pockets or round flanges are used during assembly. If the automated vision inspection system is looking for one of these geometric shapes, the vision system may lock onto a feature in the vehicle rather than the geometric mark on the airbag. Furthermore, as shown in FIG. 14, parallel edges of these shapes can be mistakenly used by the vision system to complete partial shapes. For example, if the right edge of the left hand triangle were missing due to a part covering it, the left edge of the right hand triangle could be used to complete the shape of the left hand triangle.